29 research outputs found
Observation of interstellar lithium in the low-metallicity Small Magellanic Cloud
The primordial abundances of light elements produced in the standard theory
of Big Bang nucleosynthesis (BBN) depend only on the cosmic ratio of baryons to
photons, a quantity inferred from observations of the microwave background. The
predicted primordial 7Li abundance is four times that measured in the
atmospheres of Galactic halo stars. This discrepancy could be caused by
modification of surface lithium abundances during the stars' lifetimes or by
physics beyond the Standard Model that affects early nucleosynthesis. The
lithium abundance of low-metallicity gas provides an alternative constraint on
the primordial abundance and cosmic evolution of lithium that is not
susceptible to the in situ modifications that may affect stellar atmospheres.
Here we report observations of interstellar 7Li in the low-metallicity gas of
the Small Magellanic Cloud, a nearby galaxy with a quarter the Sun's
metallicity. The present-day 7Li abundance of the Small Magellanic Cloud is
nearly equal to the BBN predictions, severely constraining the amount of
possible subsequent enrichment of the gas by stellar and cosmic-ray
nucleosynthesis. Our measurements can be reconciled with standard BBN with an
extremely fine-tuned depletion of stellar Li with metallicity. They are also
consistent with non-standard BBN.Comment: Published in Nature. Includes main text and Supplementary
Information. Replaced with final title and abstrac
Postnatal penicillin prophylaxis of early-onset group B streptococcal infection in term newborns. A preliminary study
Grand unification and cosmology
The authors show that there are many issues in which cosmology and grand unification do have things to say to each other, though the utility of some of the connections is not yet clear. (57 refs)
Leptospirose-infecção e forma subclĂnica em crianças de Salvador, Bahia Leptospiral infection and subclinical presentation among children in Salvador, Bahia
Os objetivos deste trabalho foram estimar a freqĂĽĂŞncia da leptospirose e os fatores de risco em crianças de 2 a 15 anos de idade, de ambos sexos, contactantes-domiciliares dos pacientes internados (casos-Ăndices) no Hospital Couto Maia, com diagnĂłstico de leptospirose (ELISA-IgM positivo). De 148 pessoas, dos domicĂlios dos 25 casos-Ăndices, selecionados aleatoriamente, 73 (49,3%) contatos-domiciliares foram submetidos Ă avaliação clĂnico-epidemiolĂłgica e ao mesmo teste diagnĂłstico em soros pareados. Os resultados das IgM e IgG classificaram os 73 contatos-domiciliares em trĂŞs grupos: A (infecção aguda ou recente), 30 (41,1%) casos; B (nĂŁo-infectados), 34(46,6%) crianças e C (infecção antiga), nove (12,3%). Entre os do Grupo A, cinco (16,7%) apresentaram manifestações de resfriado comum. O sexo, o grupo racial, a idade e a presença de cĂŁo no domicĂlio nĂŁo apresentaram diferenças estatĂsticas significantes, entre os grupos A e B. Todavia, nas crianças do grupo A predominaram (p<0,05): contato com água na natureza; irmĂŁo caso-Ăndice e menor de 15 anos; sexo feminino e maior de 9 anos de idade e, principalmente, a falta de coleta do lixo nos locais de residĂŞncia. Em conclusĂŁo, a leptospirose em crianças de Salvador Ă© subestimada, porque Ă© oligossintomática ou similar ao resfriado comum.<br>The purposes of this investigation were to identify the frequency and risk factors of leptospiral infection among children aged between 2 and 15 years in Salvador, Bahia, household contacts of patients (index-cases) hospitalized at Couto Maia Hospital due to Leptospira interrogans (ELISA IgM positive). Among 148 household contacts from 25 selected index-cases, clinical and epidemiological data were collected and ELISA IGM and IgG were performed in paired sera (between 20 days) from 73 (49.3%). This diagnostic method divided the 73 household contacts into three groups: group A (acute or recent leptospiral infection), 30 (41.1%) children, group B (not- infected ) 34 (46.6%) and group C, (past infection) nine (12.3%) children. In group A five (16.7%) had cold syndrome simile. No statistically significant difference was found between groups A and B for sex, race, age and presence of pet dog. However, in group A there was a statistically significant predominance (p < 0.05%) of: contact with natural water courses; index-case sibling aged under fifteen years; female sex and over 9 years old; and principally lack of appropiate trash disposal in the residential area. In conclusion, leptospiral infection in children (from 2 to 15 years of age) in Salvador is underestimated, because it is asymptomatic or presents as a cold syndrome simile